One of the most widely used animal models for Type 1 diabetes has been found to carry a virus that was previously shown to produce diabetes in other rodents, a finding that offers the possibility of new treatments for the widespread disorder.
The BioBreeding, or BB, rat naturally develops diabetes at about 2 months of age, and researchers have attributed the disease to genetics. The new findings suggest that there is indeed a genetic susceptibility but that the precipitating event is a viral infection.
The virus in question is the Ljungan virus, named after the Swedish river valley where virologist Bo Niklasson of Uppsala University discovered it in voles in 1999. Niklasson and geneticist William Klitz of the Public Health Institute in Oakland recently reported that the virus is linked to stillbirths, which are more common in diabetics than healthy women.
They have also previously reported that Ljungan virus infections can induce diabetes in voles and laboratory rodents, and that the diabetes can be reversed if the animals are treated with antiviral drugs before the destruction of insulin-secreting islet cells becomes widespread.
In the new study, reported in the current issue of the journal Diabetologia, they examined 16 BB rats from Sweden and 10 from the United States, finding that all were infected with Ljungan virus and that the infection tended to concentrate in the pancreas.
They also found the virus in 10 Wistar and five Sprague-Dawley rats from Sweden, which do not normally develop diabetes. This indicates that a genetic predisposition is also required for diabetes to develop.
They are now testing the BB rats to determine whether diabetes can be blocked by killing the virus with drugs. Results are expected in a few weeks.
The studies were funded by the U.S. National Institutes of Health and the Swedish Children's Diabetes Fund.